Here are books that can help you establish a Master IT plan:
Developing an IT Business Plan contains a Sample Budget Worksheet; Sample Staffing Plan Worksheet; Department Budget Template; Budget Notes List; Data Telecommunications Circuit Inventory;Software License Template; and Capital Budget Template.
Building a Strategic IT Plan is a 59 page reference guide.
Managing Information Technology Projects: Applying Project Management Strategies to Software, Hardware, and Integration Initiatives actually has an IT Project plan outline in the 6th chapter.
IT Management-101: Fundamentals to Achieve More seems more practical than Building a Strategic IT Plan with more diagrams and tables you can fill in to create a useful plan.
These titles should give you a good start. Forgive the Amazon.com links, I have a subscription to SkillPort Books 24/7 with full access to these titles and it was the easiest way to point to them. As far as a company to create a plan, you’re looking at hiring a consulting firm at quite a premium. If you have a university nearby you could ring the MIS department. Often students can be used for free for projects like this. A systems analysis and design or IT management class should meet your needs.